Discrimination of healthy and osteoarthritic articular cartilage by Fourier transform infrared imaging and Fisher's discriminant analysis.

Fourier transform infrared spectroscopic imaging (FTIRI) technique can be used to obtain the quantitative information of content and spatial distribution of principal components in cartilage by combining with chemometrics methods. In this study, FTIRI combining with principal component analysis (PCA) and Fisher's discriminant analysis (FDA) was applied to identify the healthy and osteoarthritic (OA) articular cartilage samples. Ten 10-µm thick sections of canine cartilages were imaged at 6.25µm/pixel in FTIRI. The infrared spectra extracted from the FTIR images were imported into SPSS software for PCA and FDA. Based on the PCA result of 2 principal components, the healthy and OA cartilage samples were effectively discriminated by the FDA with high accuracy of 94% for the initial samples (training set) and cross validation, as well as 86.67% for the prediction group. The study showed that cartilage degeneration became gradually weak with the increase of the depth. FTIRI combined with chemometrics may become an effective method for distinguishing healthy and OA cartilages in future.

[Study on the Anisotropy of Collagenours Fibers in Articular with Infrared Imaging].

Formalin solution has been widely used to solidify the organization of articular cartilage and prevent tissue decomposition in long-time measurement. However, it was rarely investigated that the structural anisotropy changes of collagen fiber (fixation) of articular cartilage when it was immersed in formalin. In this paper, Fourier transform infrared spectroscopic imaging with polarization technique was used to investigate the anisotropic structure change of collagen fiber of articular cartilage fixed in formalin through the absorbance change of Amide I and Amide II with immersing time and polarization direction. The degree of anisotropy of collagen fiber in cartilage was characterized with fitting related coefficient of absorbance. The anisotropy of Amide I and Amide II became stronger with immersing extension of articular cartilage in formalin, and the amide I showed more remarkable anisotropy. It was concluded that the formalin solution induced new crosslinks of collagen, which gradually strengthened the collagen fiber anisotropy and was helpful for the structural analysis of the articular cartilage. The study will be significant for the preparation, preservation and anisotropy research of cartilage specimen.

Discrimination of healthy and osteoarthritic articular cartilages by Fourier transform infrared imaging and partial least squares-discriminant analysis.

Fourier transform infrared imaging (FTIRI) combined with chemometrics algorithm has strong potential to obtain complex chemical information from biology tissues. FTIRI and partial least squares-discriminant analysis (PLS-DA) were used to differentiate healthy and osteoarthritic (OA) cartilages for the first time. A PLS model was built on the calibration matrix of spectra that was randomly selected from the FTIRI spectral datasets of healthy and lesioned cartilage. Leave-one-out cross-validation was performed in the PLS model, and the fitting coefficient between actual and predicted categorical values of the calibration matrix reached 0.95. In the calibration and prediction matrices, the successful identifying percentages of healthy and lesioned cartilage spectra were 100% and 90.24%, respectively. These results demonstrated that FTIRI combined with PLS-DA could provide a promising approach for the categorical identification of healthy and OA cartilage specimens.

[Apoptosis of type II alveolar epithelial cell induced by bleomycin in lung fibrotic rat].

OBJECTIVE: To investigate the effects of bleomycin (BLM) on the apoptosis of type II alveolar epithelial cell (AT II) in lung fibrotic rats and its possible mechanisms. METHODS: Totally 32 male Sprague-Dawley rats were randomly divided into sham group (n = 8) and BLM group (n = 24). Rats in sham group or BLM group were intratracheally instillated with saline or 5 mg/kg of bleomycin, respectively. One, three, and seven days after the instillation of bleomycin, 8 rats in BLM group were taken for AT II isolation and purification. Rats in sham group were used to isolate and purify AT II on 7 days after the instillation of saline. The cell cycle and apoptosis, intracellular free calcium concentration, and mitochondrial membrane potential (MMP) in AT II were determined by flow cytometry. Immunohistochemistry was performed to observe the expressions of Bax, Bcl-2, and Fas. Caspase-3, Caspase-8, and Caspase-9 activities were measured by Caspase activity detection kit. RESULTS: The ratio of S phase AT II in BLM group was significantly lower than in sham group (P < 0.05). AT II apoptosis rates on day 1 and 3 were significantly higher in BLM group than in sham group (P < 0.01). Intracellular free calcium concentrations in BLM group were significantly higher than in sham group (P < 0.05). However, MMP was significantly lower than sham group (P < 0.05). The positive rates of Bax, Fas and Caspase-3, Caspase-8, and Caspase-9 activities of BLM group were significantly higher than those of sham group (P < 0.05, P < 0.01). The positive rates of Bcl-2 on day 1 and 3 were significantly lower than those of sham group (P < 0.05). CONCLUSION: Early AT II apoptosis may be induced by bleomycin, which may be explained by the increase of intracellular free calcium concentration, depression of MMP, increased expressions of Fas and Bax, and increase of Caspase-3, Caspase-8, and Caspase-9 activities.